Observation of intra-pulse thermal effect induced double pulsing in a single-mode TEA CO₂laser

Abstract

We have observed the emission of two optical pulses as a result of a mode pushing and pulling phenomena of a thermal origin in the operation of a single-mode TEA CO2 laser. This effect arises from the intra-pulse temperature induced change of the refractive index and it can push the cavity mode, when appropriately located with respect to the centre of transition, out of lasing. Following the termination of lasing, as the temperature equilibrates, the mode is pulled back into the gain domain thereby causing the emission of the second pulse. We have provided experimental evidence in support of this mechanism and also discussed possible applications of this two-pulse laser.